You can learn about the JWM Xwindows manager by clicking on the Help icon and scrolling down and clicking JWM.

All of the main standard menus are in the .jwmrc script. You can open this with an editor and change it. For example, if you change <gdmap> to <gdmap -f />, you can then click on the Gdmap desktop icon and have it instantly do something useful.

When you make changes in jwmrc, you will usually have to exit Xwin to a prompt, and then start it up again:
# xwin jwm

There is one problem:
The next update (e.g. from 107 to 108) will replace the configurationfile with a new one, so you loose your changes.

So the best will be, to create your own submenu with your own etries, and save the lines of it in another textfile as a backup.
So after a update, you can paste your backuped lines to the new config.

There are some Tools around, that do that "grafically".
This menueditor supports JWM:
http://www.murga.org/~puppy/viewtopic.php?t=1985

If you use the "Fluxbox"-windowmanager, you can install a patch, that imports the JWM-menu.
So you can use the Fluxbox-menueditor to add personal entries, and also have access to all ofPuppys Menueentries, even after an update.
http://www.murga.org/~puppy/viewtopic.php?t=4245
http://www.murga.org/~puppy/viewtopic.php?t=4348
Mark